Hydraulic jar



W. L. MEDDERS ETAL July 30, 1957 HYDRAULIC JAR 2 Sheets-Sheet 1 FiledJune 5, 1953 We/aon L. Meoaer: Arno/ .5. Foreman, z/r.

INVENTOR.

ATTORNEYS ,Miliwv July 30, 1957 w. L. MEDDERS ElAL 2,801,078

HYDRAULIC JAR Filed June 5, 1953 2 Sheets-Sheet 2 HYDRAULIC JAR WeldonL. Medders and Arnal B. Foreman, 312, Houston,

Tex., assignors to Houston i! Field Material 6Company, Inca, Houston,Tex a corporation of Delaware Application June 5, 1953, Serial No.359,882

18 Qlaims. (Cl. 25527) This invention relates to a device for use inwell drilling operations to give a vigorous jar or impact to a string ofpipe, stuck tools and the like which are lodged in a well bore, and moreparticularly relates to such a device in which the jar is aifected byhydraulic action when the pipe or tool which is lodged in the well boreis under an upward stress and through which drilling fluid may becirculated.

In drilling wells, operations are frequently hampered because tools orthe string of pipe operating these tools become lodged in the bore holeand cannot be dislodged by usual methods of pulling or torquing from thesurface of the earth. This difiiculty has partially been overcome by thedevelopment of jarring devices designed to dislodge the tools or pipe byjarring or impacting, some of which provided a jarring action while thetools or pipe are under an upward stress which permits a continuousstrain on the tool or pipe during and after the blow which moreefiectively transmits the force of the blow to the formation from whichthe lodged article is desired to be freed. Certain of such jarringdevices of this latter type make use of gas under pressure to impart thenecessary jar, and one such device is shown in U. S. Patent No.2,265,431, issued to Robert L. Kerr on December 9, 1941. This device andother hydraulic jars cannot be used satisfactorily during ordinarydrilling operations, however, because it is not possible to circulatedrilling fluid therethrough which is necessary in the rotary drilling ofwell bores and the like.

Accordingly, it is an object of the present invention to provide ahydraulic jarring device which may be used during normal operations andthrough which drill fluid may be circulated.

In hydraulic jars, such as the device shown in U. S. Patent No.2,265,431, mentioned before, a noncompressible liquid is provided toinitially retard upward movement of the hammer element, which hammerelement is moved upwardly by gas under pressure. Considerable diflicultyhas been encountered in the operation of such devices in that the liquidand gas become intermingled which prevents efficient operation of thejar. It is, therefore, a further object of the present invention toprovide a hydraulic jar in which the gas by which the jarring action iseffected is separated from the liquid which initially retards upwardmovement of the hammer element.

A further object of the present invention is the provision of ahydraulic jar by which the jar may be easily and readily loaded for useat pressures of the order of the formation where the jarring action maybe desired.

A still further object of the present invention is the provision of sucha jar in which guide means are provided to guide the movement of thehammer element and at the same time provide adequate by-pass means forthe incompressible liquid in order that the hammer element mayefficiently be moved throughout its stroke.

Other and further objects and features will be apparent from thefollowing description of an example of the 2 invention given for thepurpose of disclosure, taken in connection with the accompanyingdrawings, where like character references designate like partsthroughout the several views, and where Figure 1 is a side elevation,partly in section, of a hydraulic jar constructed in accordance with theinvention, and shown during normal drilling operations,

Figure 2 is a cross-sectional view taken along the line 22 of Figure 1and illustrates an upper section of the tool,

Figure 3 is a cross-sectional view taken along the line 3-3 of Figure l,and illustrates a stufling box dividing the tool into two compartments,

Figure 4 is a cross-sectional view taken along the line 4-4 of Figure 1and illustrates the lower check valve assembly and guide means for thehammer element throughout its stroke,

Figure 5 is a view similar to Figure l, but illustrates the hydraulicjar after an upward stress has been applied to the lodged article andimmediately prior to jarring,

Figure 6 is a view similar to Figure l and illustrates the hydraulic jarat the moment of jarring, and

Figure 7 is fragmentary cross sectional elevation illustrating amodification of the washpipe.

Referring now to the drawings, and particularly to Figure 1, thehydraulic jar comprises an elongated, substantially tubular body 10, thelower end of which may be threaded or otherwise secured to the joint orsubstitute 12, which in turn is threaded or otherwise secured to asection of pipe or to a drilling or fishing tool, as the case may be, afragmentary portion being shown and indicated at 13. V

The body 11 has an upper chamber 14 and a lower chamber 15 formed andseparated by the stufling box 16 disposed substantially midway of thebody. As will be apparent later, the upper chamber 14 is provided withgas to effect the hammer action, and the lower chamber 15 is providedwith a noncompressible liquid to initially retard the upward movement ofthe hammer element.

Extending downwardly into the upper end of and slidable in the upperchamber 14 is a support and cocking member generally indicated by thereference numeral 17, which includes the piston 18, which mayconveniently be referred to as a cocking piston, and which fits snuglyin the upper chamber 14. As illustrated, suitable piston rings or otherpacking means 20 may be provided in the usual manner to prevent passageof gas between the sides of the piston and the inner wall of the upperchamber. The cocking and support member 17 also includes the piston rod19 which may be secured to a suitable connection 22, as seen in Figure6, by which the tool may be secured to a string of pipe for manipulationin the well bore. In order that rotation of the drill pipe to which thejarring device is secured may be transmitted to the jarring device andthrough it to articles below, the piston rod 19 may be of any suitableshape other than round, such as hexagonal as shown, in which event thebushing 24, threadedly secured to the upper end of the body 11 iscomplementarily shaped at its inner portion to cooperate with the pistonrod 19 slidable therethrough. As illustrated, the piston 18 has anexternal diameter greater than the internal diameter of the bushing 24in order that an upward pull may be exerted on the jarring device andthe device may be suspended as it is lowered or raised into and from thewell bore. 7

Located in the body 10 is the movable hammer element, generallyindicated by the reference numeral 26, which hammer element includes theupper piston 28 located in the upper chamber 14 and the lower piston 31)movable in the lower chamber 15 and connected by means of the piston rod32 slidably extending through the stufling box 16.

be similar to the cocking piston 18 and fit snugly in the upper chamber14. As is the case with piston 28, piston 28 may have suitable packingsuch as the'O-rings 21, which provide a snug fit in the cylinder 14 andprevent the escape of gas between the sides of the piston 28 and .theinner wall of the chamber 14. The stufling box 16 may contain anysuitable packing, for example, the O-ring 34 to prevent leakage of fluidbetween the upper and lower chambers 14 and 15, respectively. a

As illustrated, the piston 18 is made integral with the lower end of thesupport or piston rod 19, the piston 28 is formed integrally with thepiston rod 32 and the piston any preferred manner or made an'integralpart thereof as desired:

The lower chamber has the longitudinally-extending grooves 36 whichextend from the stufiing box 16 to a distance approximately the lengthof the piston 30 above the lower end of the chamber. The inner diameterof the lands 37 between the grooves and the inner diameter of the lowerchamber 15 below the lower end of the grooves 36 is the same and of adiameter to snugly receive the piston Thus, the lands 37 serve as guidesfor the movement of the piston 30 and the grooves 36 provide by-passmeans to permit bypassing of a noncompressible liquid about the piston30 as it moves in the container 'or cylinder 15. Thus, when the piston30 is in the position illustrated in Figure. l, the leakage of liquidabout the piston 30 will be slow thereby initially retarding upwardmovement thereof; however, when the piston 30 moves out of the confinedspace of the lower portion of the cylinder 15, the liquid is readilybypassed in the grooves 36, thereby permitting substantiallyuninterrupted upward movement of the piston 30.

To-facilitatedownward movement of the piston 30 there is'disposedtherein a check-valve arrangement 38 which prevents flow of fluidthrough the piston 30 when 'it is moving upwardly, and permits flow offluid through the pistonfit) as it is moved downwardly so that thehammer element may be readily cocked and the piston 31) located in theconfined space at the lower portion of the lower chamber or cylinder 15.Any suitable check-valve arrangement may be utilized which is soconstructed and arranged to prevent the flow of liquid. downwardly andlower ends to permitentry of the liquid and gas into chambers 15 and 14,respectively. It is advantageous to provide the inlet ports for thechambers 14 and 15 at the stufling box inasmuch as the metal is thickerat this point and permits of maximum strength and compactness.

In order that drill fluid may be circulated through the tool, a washpipe 44 is threaded into the lower end of the cooking piston 18 formedat the lower end of the support 19,- which wash pipe extends downwardlyand is slidable through the piston 28 in the upper cylinder 14,

the'piston rod 32, the lower piston 39 and through the tool joint 12. Asuitable stufiing box is provided in the lower portion of the tool joint12 by providing the packing 46 which is compressed into sealingengagement with the outer wall of the wash pipe 44 by means of thethreaded gland 48. Thus, the wash pipe 44 is free to slide throughoutthe jar with the movement of the upper cocking piston 18, however,suflicient room must be provided for the runout of the wash pipe 44 inthe tool or pipe generally indicated. by the numeral 13. Thus fluidflowing in the piston rod 19 from the pipe thereabove (not shown) flowsthrough the wash pipe 44 and empties into the pipe section or tool 13below.

The wash pipe may be fixed with respect to the body 16 and slide withrespect to the pistons as illustrated in the modification in Figure 7where the wash pipe 44a is fixed in the body 10 by complementary threads11 on the wash pipe 44a and in substitute 12a. The cocking and supportmember 17 slidably and snugly receives the wash pipe 44a whichextendsfar enough toward the top of the jar that the Wash pipe 44a remains in.the cocking piston 18 when the cocking piston is at its uppermost joint.Suitable packing such as the O-ring in the cocking piston 18 preventsleaking of fluid into the upper chamber 15 from the cooking and supportmember 17. V

In operation, the lower chamber 15 may substantially be filled with anoncompressible liquid through the port 40 and the upper chamber belowthe upper piston 28 may be filled with a gas under high pressure throughthe port 4-2. Ordinarily, the pressure of the gas would be of the order'of the pressures of the formation at which the tool is to be used;although, other pressures may be used. The

jar then may be threaded in a string of pipe for ordinary V drillingoperations or may be threaded to a string of pipe and a fishing tool forrunning ordinary fishing operations, as desired.

Assuming that the hydraulic jar is connected in a string of pipe duringnormal drilling operations, fluid may be circulated downwardly throughthe string of pipe to which it is connected extending to the surface(not shown). through the tool and downwardly to the bit and out toperform the usual function. In the event the bit and/or part of thestring of pipe to which it is connected becomes stuck or lodged in thewell bore, the pipe and/ or bit may be jarred loose in the followingmanner. All or a portion of the weight of the string of pipe above thetool is permitted to bear on the jar which lowers the support 19 therebymoving the cocking piston 18 downwardly, which engages the upper piston28 and moves the hammer element downwardly into position as illustratedin Figure 1.

H This downward movement serves to cock the hammer element. When movingthe lower piston 30 downwardly, the noncompressible liquid will flowrapidly through the piston 30 thereby permitting rapid and ready cockingof the hammer element.

When it is desired to exert a jar upon stuck pipe. or

tools or both, the string of pipe to which the support 19 is connectedis elevated at the surface to raise the cocking piston 18 to theposition illustrated in Figure 5. Due to the slowness of leakage ofliquid about the lower piston 30 in the confined space at the lower endof the lower chamber 15, the hammer element-which is forced upwardly bythe pressure of the gas under the upper piston 28 is initiallyrestrained from upward movement and considerable upward strain may beexerted on the hydraulic jar and pipe and tools to which it is'connected before the jarring action takes place. After a predeter-.mined time interval, the lower piston 30 will move out of the confinedspace at the lower portion of the lower chamber 15 thereby permittingthe liquid to bypass the lower piston 30 in the slots 37. It seemsapparent that a tremendous pressure will be exerted on the under side ofthe upper piston 26 and the upper chamber 24 there-.

by urging the hammer element upwardly violently. De-

pending upon the length of the piston rod 32 connecting the lower piston30 and upper piston 26, a violent impact will occur between the uppersurface 50 of the piston 26 which may be thought of as a hammer surface,and the lower surface 52 of the cocking piston 20 which is in efiect ananvil surface. This arrangement is illustrated in Figure 6 and shows theparts in the position at the moment of impact.

If desired, however, the piston rod 32 may be shortened so that theupper surface 54 of the lower piston 30 is the hammer surface, and thedownwardly facing annular shoulder 56 of the stufiing box 16 is theanvil surface. Obviously, if desired, both of these surfaces, that isthe anvil surfaces 52 and 56 may be impacted simultaneously by thehammer surfaces 50 and 54, respectively.

Thus, a violent jarring action is provided to the string of pipe andtools secured thereto, which jarring action takes place when the stringof pipe and tools are under an upward strain. The cycle of jarring maybe repeated as many times as desired by merely lowering the string ofpipe from the surface and then taking an upward stress thereon. When thetool or pipe has become dislodged, the drilling operation may becontinued without the necessity of removing the tool or string of pipeto the surface or the pipe and hydraulic jar may be removed, as desired.

During the course of cocking the jar and the jarring movement, themovement of the pistons will be guided as they are closely confined inthe upper and lower piston chambers 14 and 15, respectively, althoughsuitable bypass means are provided in the lower chamber 15 whichprevents excessive vibration and wear on or possible fouling of thetool.

It is apparent that numerous changes in the details and the arrangementof parts may be made, and the jar is well adapted to carry out of theobjects set forth and other objects inherent therein.

Accordingly, it is desired to be limited only by the spirit of theinvention and the scope of the appended claims.

What is claimed is:

l. A hydraulic jar for use in a well bore comprising; a substantiallytubular first member adapted for engagement within the well bore; apartition separating the first member into upper and lower pistonchambers; a passageway extending through the partition axially of thefirst member; a supporting member having a part extending into suchupper piston chamber and movable relative to the first member; engagingstop means on the first member and supporting member to limit upwardmovement of the supporting member relative to the first member; a hammerelement comprising an upper piston located in the upper piston chamberand movable relative to the first member, a piston rod secured to theupper piston and slidably extending downwardly through the passageway inthe partition, and a lower piston secured to the piston rod and movablylocated in the lower piston chamber; means in the partition to sealinglyengage the partition and piston rod against fluid passage; the lowerpiston chamber having a small bore closely fitting the lower piston andhaving fiuid bypass means between the partition and small bore; a washpipe in the first member communicating with fluid passageways above andbelow the jar; a substantially noncompressible liquid substantiallyfilling the lower piston chamber; gas under pressure within the upperpiston chamber under the upper piston for urging the hammer elementviolently upward; said part of the supporting member extending into saidupper piston chamber engaging said hammer element to force the lowerpiston into the small bore thereby cocking the jar on downward movementof the supporting member relative to the first member; and slow leakageof liquid past said lower piston in the small bore portion of the lowercylinder upon disengagement of the supporting member from the hammerelement delaying for a substantial period the occurrence of a blow bysaid hammer element until the supporting member may be elevated toengage the engaging means and exert a direct upward stress on said firstmember.

2. The hydraulic jar of claim 1 where the fluid bypass means compriseslongitudinally extending grooves and lands from the partition to thesmall bore, the internal diameter of the lands being the same as theinternal diameter of the small bore.

3. The hydraulic jar of claim 1 including Valve means in the partitionthrough which liquid is inserted into the lower piston chamber and gasunder pressure is inserted into the upper piston chamber.

4. The hydraulic jar of claim 1 in which the part of the supportingmember extending into the upper piston chamber is slidable in andnon-rotatably secured to the first member.

5. A hydraulic jar for use in a well bore comprising; a substantiallytubular first member adapted for engagement within the wel bore; apartition separating the first member into upper and lower pistonchambers; a passageway extending through the partition axially of thefirst member; a supporting member having a part extending into suchupper piston chamber and movable relative to the first member; engagingstop means on the first member and supporting member to limit upwardmovement of the supporting member relative to the first member; a hammerelement comprising an upper piston located in the upper piston chamberand movable relative to the first member, a piston rod secured to theupper piston and slidably extending downwardly through the passageway inthe partition, and a lower piston secured to the piston rod and movablylocated in the lower piston chamber; means in the partition to sealinglyengage the partition and piston rod against fluid passage; the lowerpiston chamber having a small bore closely fitting the lower piston andhaving fluid bypass means between the partition and small bore; asubstantially noncompressible liquid substantially filling the lowerpiston chamber; gas under pressure within the upper piston chamber andunder the upper piston for urging said hamrner element violently upward;said part of the support ing member extending into said upper pistonchamber engaging said hammer element to force the lower piston into thesmall bore portion thereby cocking the jar on downward movement of thesupporting member relative to the first member; and slow leakage ofliquid past said lower piston in the small bore portion of the lowercylinder upon disengagement of the supporting member from the hammerelement delaying for a substantial period the occurrence of a blow bysaid hammer element until said supporting member may be elevated toengage the engaging means and exert a direct upward stress on said firstmember.

6. The hydraulic jar of claim 5 where the fluid bypass means compriseslongitudinally extending grooves and lands from the partition to thesmall bore, the internal diameter of the lands being the same as theinternal diameter of the small bore.

7. The hydraulic jar of claim 5 in which the part of the supportingmember extending into the upper piston chamber is slidable in andnon-rotatably secured to the first member.

8. A hydraulic jar for use in well bores comprising; a hollow bodymember; a partition separating the hollow body member into upper andlower piston chambers, a passageway extending through the partitionaxially of the body member; an upper member adapted to be connected to astring of pipe, said upper member having a portion extending into theupper piston chamber; a first piston disposed on the upper member andmovably located in the upper piston chamber, said first piston having ananvil surface at its lower portion; stop means in the upper end of theupper piston chamber for limiting upward movement of the upper memberrelative to the upper piston chamber; a hammer element comprising asecond piston located below the first piston in the upper piston chamberand movable relative to the first piston, said second piston having ahammer sur face at its upper portion, a piston rod secured to the secondpiston and slidably extending downwardly through a between the partitionand small bore; a subs antially noncompressible liquid substantiallyfilling the lower piston chamber; gas under pressure in the upper pistonchamber under the second pistou'for urging said hammer element upwardly;said first piston engaging said second piston to force said third pistoninto the small bore portion thereby cocking the jar on downward mov menof he upper memberrelative to the, upper piston chamber; and the slowleakage of liquid past said third piston in the small bore portion ofthepiston chamber upon disengagement of the first piston from the secondpiston delaying the. occurrence of a, blowby said hammerelement untilsaid upper member may be elevated to engage the first piston and stopmeans and engage and exert a direct upward stress on said body member.

9. The hydraulic, jar or claim 8 including a ash pipe extending from theupper member, through the first piston, and hammer element, said wash,pipe being in registry with fluids passageways above and below the jarwhereby fluid may be circulated through the jar.

10. The hydraulic jar of claim 8 where the fluid bypass means compriselongitudinally extending grooves andlands. from the partition tothe'srnall bore, the internal diameter of the lands beingrthe same asthe internal diameter'of the, small bore." t

11. The hydraulic jar'of claim 8 in which the portion of the uppermember extending into the; upper piston chamber is slidable. in andnon-rotatably secured to the body member.

12 A, hydraulic. jar for use inwell-bores and adapted to be connected toa string of pipe comprising; a hollow body member, a partitionseparating the body member into, upper and lower piston cylinders; apassageway ex tending through the partition axially of the body member;an upper member adapted to be secured to the string of pipe forsupporting said body member and extending intothe upper pistonrcylinderand movable relative to the body member; arfirst piston secured to theupper member and movable in said upper piston cylinder; stop means inthe upperpistonchamber engageable by said first piston on upwardmovement thereof relative to said upper piston cylinder; a hammerelement comprising a second piston located in the upper piston cylinderbelow and movable relative, to the first piston, a piston rod secured tothe second piston and slidably extending downwardly through thepassageway in the partition, and a third piston secured to the pistonrod and movably' disposed in the; lower piston, cylinder; means in thepartition to sealingly engage the partition and .piston rod againstfluid passage; the lower piston cylinder haying a small bore closelyfitting the third piston. andhaving fluid bypass meansgbetwe'en thepartition and the small bore; a substantially noncompressible liquidsubstantially filling the lower piston cylinder; gas under pressure inthe upper piston cylinder'below the second piston for violently urgingsaid hammer element upwardly; a hammer surface at the upper portion ofthe third piston and an anvil surface at the lower portion of thepartition engageableby said hammer surface, for imparting a violent bolwto said body member; said first piston engaging said second piston toforce said third piston into the small bore thereby cocking the jar ondownward movement of' the upper member relative to the upper pistoncylinder; and slow leakage of liquid past saidthird piston in the smallbore of the lower cylinder upon disengagement of thefirst piston fromthe second piston initially delaying the occurrence of a blow by saidhammer surface until said upper member may be elevated relative to sai'dupperzpiston cylinder and said first piston .8 may e gage aid s p meansand; exert a direct upward stress on said body member. V V

13- Th hydraulic jar of 'elaimllincludin at fluid passageway extendingthrough the upper member, first piston hammer element. and in registrywith the passage in the string of pipe whereby fluid maybe circulated th th jars a 14. The hydraulic jar of claim 12 where the fluid by-passmeans comprises longitudinally extending grooves and lands from, thepartition to the small bore, said lands being of the same internaldiameter as the internal diameter, of the small bore. r

15. A hydraulic jar for use in well bores and adapted to be connected toa string of pipe comprising; a sub-. stantially tubular body; a Stu ngbox separating the body into upper and lower piston chambers; a hollowsup.- porting member adapted'to be secured to the string of pipe andextending into the upper piston chamber and movable relative to thebody;engaging stop, means on the body and supporting member, to limit uplwardmovement of; the supporting member relative to the body; a hammerelement comprising anupper piston located in the upper pistonrchamberand movable relative. to the body; a piston rod secured to the upperpiston and slidably extending through the stuffing' box, and a lowerpiston secured to the piston rod and movably located in the lower pistonchamber; the lower piston chamber having a small bore at itslower endclosely fitting the. lower piston and having longitudinally extending,grooves and lands 'fromrthe stuflingibox to the small bore, the inter:

' said upper piston to force the lower piston into the small boreportion thereby cocking the jar on downward movement of; the supportingmember relative to the body; and thereafter upward movement of saidsupporting member relative to the body engaging said engaging stop meansand exerting a direct upward stress on said body.

16, A hydraulicjar for use in well bores and adapted to be secured to astring of pipe comprising; a substantially tubular body; a stufiing boxseparating the body into upper and lower piston chambers; a'hollowsupporting member adapted; to be, secured to the stringof pipe andextending into the upper piston chamber and movable, relative to thebody; engageable stop means on the body and supporting member to limitupward movement of the supporting; member relative to the body;

7 a hammer element; comprising an upper piston located substantiallynoncompressible liquid substantially filling the lower piston chamber;gas under pressure in the upper piston chamber below the upper pistonfor violently urging the hammer element upwardly; a wash pipe connectedto the, supporting; member and extending downwardly through the upperpiston, hammer element, and lower piston chamber for circulating fluidthrough the jar; that portion of; said supporting member extending intosaid upper piston chamber engaging said upper piston to force the lowerpiston into the small bore thereby cocking the jar on downward movementof the supporting member relative to the body, and thereafter upwardmovement of said supporting member relative to the body engaging theengageable stop means and exerting a direct upward stress on said body.

17. The hydraulic jar of claim 16 including valve means at the stuflingbox for injecting and Withdrawing liquid in the lower piston chamber andgas under pressure in the upper piston chamber.

18. The hydraulic jar of claim 16 including a check valve in the lowerpiston preventing passage of the liquid downwardly through the lowervalve and permitting passage of the liquid upwardly through the lowerpiston.

References Qited in the file of this patent UNlTED STATES PATENTS1,804,700 Maxwell May 12, 1931 2,126,241 Black Aug. 9, 1938 2,265,431Kerr Dec. 9, 1941 2,309,872 Shafier et a1. Feb. 2, 1943 2,499,695 StormMar. 7, 1950

